disc: redact Debug for AacsState/Key/HandshakeResult (test-guarded)

AacsState (public via Disc.aacs) and Key (the decrypt_with key-transport enum)
are crate-root re-exported and carried VUK/unit/read-data keys + volume id on
#[derive(Debug)]; HandshakeResult carried the VID + AACS 2.0 bus key. Manual
Debug impls print shape only, guarded by red->green tests.

src/css/mod.rs

@@ -390,7 +390,10 @@ mod tests {
             !dbg.contains("213"),
             "CssState Debug leaked the title key: {dbg}"
         );
-        assert!(dbg.contains("redacted"), "CssState Debug missing marker: {dbg}");
+        assert!(
+            dbg.contains("redacted"),
+            "CssState Debug missing marker: {dbg}"
+        );
     }
 
     // ── is_scrambled ───────────────────────────────────────────────────────